A large, long-running crack was plainly visible across the ice shelf on the Pine Island Glacier during an overflight by NASA's DC-8 airborne science laboratory during an Operation IceBridge flight Oct. 14. A follow-up flight Oct. 26 collected more data on the ice shelf and the crack. The area beyond the crack that could calve in the coming months covers about 310 square miles (800 square kilometers). (NASA / Michael Studinger)

NASA's DC-8 airborne science laboratory conducted a second Operation IceBridge sortie over the Pine Island Glacier in Antarctica Oct. 26 after discovering a huge crack many miles long across the glacier's ice shelf during a prior flight Oct. 14.

Mission Directors Walter Klein and Adam Webster take a break at the mission director's console on NASA's DC-8 flying laboratory to show off the mission logo during an Operation IceBridge flights over Antarctica. (NASA photo) The science team aboard the converted jetliner collected data over what they are calling a significant fissure which transects a large portion of the terminal glacier. IceBridge scientists believe they are witnessing the separation of an enormous portion of the glacier and this survey is the first of its kind during this type of a glacial event.

Earlier in the week, the IceBridge mission team kept up the rapid pace of long-duration flights to gather data on ice thickness and movement from a suite of seven specialized science instruments on board the aircraft.

On Monday Oct. 24 a 10.7-hour mission took them over the Alexander Island area in the Antarctic Peninsula, with the pilots carefully flying the aircraft over the same flight tracks flown in the 2009 and 2010 IceBridge campaign. Clear conditions allowed for excellent data collection by the Airborne Topographic Mapper and the Digital Mapping System, an airborne digital camera that acquires high-resolution natural color and panchromatic imagery, which scientists will now compare to data obtained in prior years.

Ice-coated mountain ridgelines on Alexander Island, one of the largest islands off Antarctica, protrude through the snow and ice of Antarctica in this view from NASA's DC-8 airborne science laboratory during a Fall 2011 Operation IceBridge flight Oct. 24. (NASA / Michael Studinger) On Tuesday Oct. 25, the flying laboratory made an 11.7-hour flight that included almost eight hours of low-altitude science data collection over the Weddell Sea area from the northeastern peninsula region to the Brunt Ice Shelf region on the southeast. Good weather over most of the route aided observation and navigation, with low clouds obscuring observation of sea ice for only about five percent of the route.

As of Oct. 27 – a no-fly day for aircraft maintenance and crew rest – the DC-8 had flown about 60 percent of its 250 flight hours allocated for the Fall 2011 Operation IceBridge campaign. Several of the flights were coordinated with overflights of the CloudSat and the European Space Agency's CryoSat-2 satellites, which also collect data on thickness and movement of the Antarctic ice fields that cover about 98 percent of the continent.

The DC-8 is scheduled to return to its base at the Dryden Aircraft Operations Facility in Palmdale, Calif., on Nov. 22.

Operation IceBridge was begun in 2009 to bridge the gap in data collection after NASA's ICESat-1 satellite stopped functioning and when the ICESat-2 satellite becomes operational in 2016. By comparing the year-to-year readings of ice thickness and movement both on land and on the sea, scientists can learn more about the trends that could affect sea-level rise and climate around the globe.